1. Field of the Invention
The present invention relates generally to timing diagnostics and, more particularly, to a method of measuring angular degree relationship between the camshaft and crankshaft of an engine.
2. Description of the Related Art
Increasingly stringent hydrocarbon, nitrous oxide, and carbon monoxide emission standards are being placed on the industry through government regulation. Unwanted emissions can be caused when a timing deficiency between the camshaft and crankshaft exists. Currently, to determine whether a deficiency has occurred, service technicians must disassemble the front of the engine to inspect visually, or use a timing tool. A technique using a two-channel oscilloscope is available. But the oscilloscope readings are subject to operator interpretation. Moreover, oscilloscopes are not readily available to all automobile service technicians. Physical inspection of camshaft and crankshaft timing is especially difficult when two camshaft gears exist and is virtually impossible without mechanical disassembly or "degree marking" of the engine.
It is also known in the art that in belt, chain, or gear driven camshaft engine designs, timing belt, timing chain, or gear slippage can occur. Excessive wear or stretching can also cause the timing apparatus to slip. If such slippage does occur, misalignment between the camshaft and crankshaft will result. The cause of timing belt, chain, or gear slippage is commonly the result of low belt, chain, or gear tension. Such slippage can also be attributed to debris entering the timing cover or wear on the timing apparatus due to high engine mileage. Timing belt, chain, or gear slippage may lead to such undesirable conditions as excessive emissions, poor engine performance, bent valves, or an aperture being punched in the cylinder head or piston damage.
It is therefore desirable in the art of vehicles to have a timing diagnostics method which internally determines the camshaft and crankshaft timing relation for easy retrieval by a service technician and further denotes timing apparatus slippage.